SEI-component formation on sub 5 nm sized silicon nanoparticles in Li-ion batteries: the role of electrode preparation, FEC addition and binders

Jaumann, Tony; Balach, Juan; Klose, Markus; Oswald, Steffen; Langklotz, U.; Michaelis, Alexander; Eckert, J.; Giebeler, Lars

doi:10.1039/c5cp03672k

Cited by 141 publications

(169 citation statements)

References 52 publications

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“…38 As it was reported earlier in the literature, FEC is reduced at more positive potentials than EC and EMC, thereby forming an SEI layer on the active material particles, which significantly reduces further electrolyte decomposition. [39][40][41] Cycling performance in SiG//LFP cells.-The cycling performance of the silicon-graphite electrodes (1.8-2.3 mAh cm −2 ) was investigated vs. capacitively oversized LiFePO 4 electrodes (∼3.5 mAh cm −2 ). To fully utilize the theoretical specific capacity of the different silicon-graphite electrodes, the cutoff potentials were set to 0.01 V vs. Li/Li + during lithiation (3.44 V cell voltage) and 1.25 V vs. Li/Li + during delithiation (2.2 V cell voltage).…”

Section: Resultsmentioning

confidence: 99%

Differentiating the Degradation Phenomena in Silicon-Graphite Electrodes for Lithium-Ion Batteries

Wetjen

Pritzl

Jung

et al. 2017

J. Electrochem. Soc.

154

173

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Silicon-graphite electrodes usually experience an increase in cycling performance by the addition of graphite, however, the relation of the silicon/graphite ratio and the aging mechanisms of the individual electrode and electrolyte compounds still requires a more fundamental understanding. In this study, we present a comprehensive approach to understand and quantify the degradation phenomena in silicon-graphite electrodes with silicon contents between 20-60 wt%. By evaluating the cycling performance and total irreversible capacity of silicon-graphite electrodes vs. capacitively oversized LiFePO 4 electrodes in presence of a fluoroethylene carbonate (FEC)-containing electrolyte, we demonstrate that the aging of silicon-based electrodes can be distinguished into two distinct phenomena, which we describe as silicon particle degradation and electrode degradation. Cross-sectional scanning electron microscopy (SEM) images and a detailed analysis of the electrode polarization upon cycling complement our discussion. Further, we deploy post-mortem 19 F-NMR spectroscopy to (i) quantify to loss of moles of FEC in the electrolyte and correlate this with the amount of charge that was exchanged by the silicon-graphite electrodes, (ii) estimate the pore volume of the silicon-graphite electrodes that is occupied by FEC decomposition products, and (iii) Silicon-based electrodes are very promising candidates to enable the next generation of Li-ion batteries with energy densities on the cell level beyond 350 Wh kg −1 . 1,2 In contrast to conventional intercalation anode materials, such as graphite (LiC 6 , 372 mAh g −1 , 890 Ah L −1 ), the specific capacity of silicon alloy electrodes is significantly higher (Li 15 Si 4 , 3579 mAh g −1 , 2194 Ah L −1 ). 3 Nonetheless, commercialization of silicon-based electrodes is still hampered because of two major challenges: 4 (i) Large volume expansions up to 280% upon repeated (de-)lithiation of silicon particles deteriorate the electrode integrity, thus causing isolation of active material. [5][6][7] The formerly reported pulverization of micron-sized silicon particles due to mechanical stress upon repeated volume expansion has been partially solved by using nanometer-sized particles. However, reduction of the silicon particle size also leads to inferior electronic conduction due to more numerous interparticle contacts, and higher solid-electrolyte-interphase (SEI) losses due to the larger relative surface area. [8][9][10] (ii) Continuous side reactions at the silicon/electrolyte interface caused by repeated volume expansion and contraction result in ongoing electrolyte decomposition and in a gradual loss of active lithium. 8In the course of this, SEI-forming additives in the electrolyte, e.g., FEC, are depleted, which was shown to result in a significant increase in cell polarization and a concomitant rapid capacity drop. 8,11 Various strategies have been proposed to overcome the detrimental effects associated with the volume expansion during (de-)lithiation of silicon and to reduce conc...

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Section: Resultsmentioning

confidence: 99%

Differentiating the Degradation Phenomena in Silicon-Graphite Electrodes for Lithium-Ion Batteries

Wetjen

Pritzl

Jung

et al. 2017

J. Electrochem. Soc.

154

173

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“…The results are discussed in context to our recent findings in alkyl carbonates as electrolyte for LIB. 32 The role of organic and inorganic compounds, in particular Li 2 O and LiF, as typical interfacial components on silicon will be highlighted.…”

Section: A558mentioning

confidence: 99%

Role of 1,3-Dioxolane and LiNO₃Addition on the Long Term Stability of Nanostructured Silicon/Carbon Anodes for Rechargeable Lithium Batteries

Jaumann

Balach

Klose

et al. 2016

J. Electrochem. Soc.

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In order to utilize silicon as alternative anode for unfavorable lithium metal in lithium -sulfur (Li-S) batteries, a profound understanding of the interfacial characteristics in ether-based electrolytes is required. Herein, the solid electrolyte interface (SEI) of a nanostructured silicon/carbon anode after long-term cycling in an ether-based electrolyte for Li-S batteries is investigated. The role of LiNO 3 and 1,3-dioxolane (DOL) in dimethoxy ethane (DME) solutions as typically used electrolyte components on the electrochemical performance and interfacial characteristics on silicon are evaluated. Because of the high surface area of our nanostructured electrode owing to the silicon particle size of around 5 nm and the porous carbon scaffold, the interfacial characteristics dominate the overall electrochemical reversibility opening a detailed analysis. We show that the use of DME/DOL solutions under ambient temperature causes higher degradation of electrolyte components compared to carbonate-based electrolytes used for Li-ion batteries (LIB). This behavior of DME/DOL mixtures is associated with different SEI component formation and it is demonstrated that LiNO 3 addition can significantly stabilize the cycle performance of nanostructured silicon/carbon anodes. A careful postmortem analysis and a discussion in context to carbonate-based electrolyte solutions helps to understand the degradation mechanism of silicon-based anodes in rechargeable lithium-based batteries. Silicon is a highly attractive anode material for rechargeable Liion batteries (LIB) and post LIB systems owing to its high capacity and comparable discharge potential to lithium metal. Considerable progress has been achieved in recent years to tackle the peculiarities of silicon during de-/lithiation.1-2 The enormous volume expansion which causes fracture of individual particles and a low reversibility could be addressed by hierarchically designed nano-sized and amorphous silicon structures.3-6 However, it was shown that among other parameters the electrochemical performance of particularly nanostructured silicon significantly depends on the chosen electrolyte. [7][8][9] This observation is mainly caused by the characteristics of the interfacial layer strongly related to the surface area of the electrode material which is especially high on nanostructures. The interfacial layer, commonly known as solid-electrolyte-interface (SEI), is a surface film typically formed in the initial cycles by decomposition of electrolyte components. Because of the large volume expansion of silicon during lithiation, the SEI likely cracks and is regenerated causing continuous electrolyte consumption and high degradation. In order to reduce degradation and apply silicon as high-performance anode in rechargeable Li-based batteries, a profound knowledge of the interfacial characteristics is necessary. The SEI on silicon is typically studied in carbonate-based electrolytes since silicon is majorly considered as alternative anode for graphite in LIB. [10][11][12][13] Howeve...

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“…From the F 1s peaks, it was observed that both Si NEs exhibited a large amount of LiF at 685 eV. 23,24 In the case of FEC addition, the peak for LiF was enhanced and a relatively large peak at ³687 eV due to C-F bonding was confirmed, indicating the presence of -CHF-OCO 2 -type compounds derived from FEC on the Si NE. In contrast, when FEC was not added, the Si NE exhibited a large number of various types of C 1s peaks derived from decomposition of the PC solvent by electrochemical reduction and an O 1s peak from a byproduct of Li 2 CO 3 at ³532 eV.…”

Section: Investigation Of Solid-electrolyte Interface Films On LImentioning

confidence: 90%

“…In contrast, when FEC was not added, the Si NE exhibited a large number of various types of C 1s peaks derived from decomposition of the PC solvent by electrochemical reduction and an O 1s peak from a byproduct of Li 2 CO 3 at ³532 eV. 23,24 From research in the field of LIBs, 25 it is well known that the PC solvent is decomposed on the Si NE surface and mainly forms a polymer-like SEI component with Li 2 CO 3 as a byproduct, which increases the charge-transfer resistance at the Si NE and deteriorates the cell Electrochemistry, 85(10), 656-659 (2017) performance, especially with respect to cyclability. Similar SEI components were confirmed for Li pre-doping without FEC; however, the chemical composition of the SEI film was changed by the FEC addition.…”

Section: Investigation Of Solid-electrolyte Interface Films On LImentioning

confidence: 99%

Stabilization of Si Negative Electrode by Li Pre-doping Technique and the Application to a New Energy Storage System

et al. 2017

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To extend the cyclability of a hybrid capacitor using Li pre-doped Si negative electrodes (NEs) (Si-CAP), we applied a polyimide binder and fluoroethylene carbonate (FEC) as additives in the Li pre-doping step. This binder successfully improved the cyclability by fixing Si nanoparticles as the NE active material on the Cu foil current collector to resist the volume change caused by Li-Si alloying. After Li pre-doping, there were no cracks on the Si NE surfaces, which had been observed in previous work using sodium carboxymethyl cellulose binder. Furthermore, FEC addition into the electrolyte at Li pre-doping improved homogeneity of the Li-Si alloying. As a result, a large amount of Li was pre-doped to the Si NE and a lower open-circuit potential was maintained. A Si-CAP cell of [Li alloyed Si | activated carbon] using polyimide binder exhibited relatively stable charge/discharge behavior and cyclability was maintained up to 800 cycles. Stability of the charge/discharge performance of FEC-containing Si-CAP was improved by formation of a LiF-rich solid-state interphase film on the Si NE. X-ray photoelectron spectroscopy revealed suppression of decomposition of the propylene carbonate solvent by electrochemical reduction.

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SEI-component formation on sub 5 nm sized silicon nanoparticles in Li-ion batteries: the role of electrode preparation, FEC addition and binders

Cited by 141 publications

References 52 publications

Differentiating the Degradation Phenomena in Silicon-Graphite Electrodes for Lithium-Ion Batteries

Differentiating the Degradation Phenomena in Silicon-Graphite Electrodes for Lithium-Ion Batteries

Role of 1,3-Dioxolane and LiNO₃Addition on the Long Term Stability of Nanostructured Silicon/Carbon Anodes for Rechargeable Lithium Batteries

Stabilization of Si Negative Electrode by Li Pre-doping Technique and the Application to a New Energy Storage System

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SEI-component formation on sub 5 nm sized silicon nanoparticles in Li-ion batteries: the role of electrode preparation, FEC addition and binders

Cited by 141 publications

References 52 publications

Differentiating the Degradation Phenomena in Silicon-Graphite Electrodes for Lithium-Ion Batteries

Differentiating the Degradation Phenomena in Silicon-Graphite Electrodes for Lithium-Ion Batteries

Role of 1,3-Dioxolane and LiNO3Addition on the Long Term Stability of Nanostructured Silicon/Carbon Anodes for Rechargeable Lithium Batteries

Stabilization of Si Negative Electrode by Li Pre-doping Technique and the Application to a New Energy Storage System

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Role of 1,3-Dioxolane and LiNO₃Addition on the Long Term Stability of Nanostructured Silicon/Carbon Anodes for Rechargeable Lithium Batteries